It is known that in some cases it is desirable to mix a fuel gas to be burned with an oxidant external to the torch. For example, in U.S. Pat. No. 3,204,682 to Teleshefsky et al, a torch is shown which is suitable for this purpose. The Teleshefsky et al torch comprises a body portion 4 having a torch face plate portion 5. A number of gas tubes 17 are welded or soldered into a plate 9 separating first and second manifolds 10 and 13. The tips of the gas tubes 17 extend through holes 18 in the torch face plate 5. The holes 18 are broached to provide spaced annular passages 20 around the tubes 17, such that the annular passages extend from the manifold 13 to the exterior surface of the torch face plate 5, and the tubes 17 extend from the first manifold 10 through the second manifold 13 and to the exterior surface of the torch face plate 5.
As described in the Teleshefsky et al patent, the torch assembly is made entirely of metal, and the tubes 17 are preferably silver-soldered to the plate 9 separating the first and second manifolds. This assembly is then assembled to the torch body portion 4. In order that this assembly can be made, the alignment of the ends of the tubes 17 to be received in the holes 18 drilled in the face plate 5 is critical. Such a torch might be difficult to manufacture. Moreover, the Teleshefsky et al torch requires that the oxidant and fuel gases be supplied in concentric passages; this is not always desirable, and places a significant constraint on the flame pattern.
It is sometimes additionally desirable to supply materials other than the oxidant and fuel gases to the vicinity of the flame. The Teleshefsky et al patent teaches no method of supplying such additional materials to the flame for deposition or any other purpose.